Answer Happy

D E Weed1 2.1 Weed3 2.5 2.1 A B AM Humboldt Oregon 2 16 16.4 3 7.4 17.6 4 15.8 8.9 S 14.5 20.4 6 7.8 9.8 7 14.2 10.7 17.5 9 7.4 10 00 AM 2.1 2.7 2.4 1.8 2.9 2.4 2.3 2.2 1.9 2.2 2.3 1.9 2 10 11 12 13 2.2 2.4 2.5 2.4 2.3

POWER and Sample size for a 2-Sample test: • Steps 1-5: For the following problem run a brief 2-sample t-test with the assumption of equal variances. • Use R code as shown in the example at the end of lecture in Week 12 Day 1. . Consider your hypothesis test as a pilot study and the prompt of the data collector to determine the direction of your one talled test Step 6: Then determine the power of the test you just ran. • Step 7: Interpret the power value with an English sentence. Step 8: Then determine the optimal sample size that would provide for a level of significance of a 0.05 and a power of 1-0 -0.80 for a follow-up study.

A Grouping of Channeled Whelks 24.3) A graduate student proposes for her Senior project that the whelk density on the coast of Humboldt County are smaller than that found off the Central Oregon coast. She begins with a pilot study at 8 random locations on the Humboldt county coast and 6 random locations off the Oregon coast. At each site she submerges a frame of 0.25 square meters on the sea floor at high tide and counts the number of whelks present within each frame. Does the Humboldt county coast have a smaller population density of whelks than that found off the Oregon coast? Image by Marie Gardner • image source from www.focusonnature.com: Channel Whelks 24.3) Step 1: Preliminary Checks • The data sets are collected from independent and random samples. . We assume that both data sets pass va normality test by the Anderson-Darling normality test, as we are using mean values.

24.3) Step 2 Declare the variables for this hypothesis test: English text equivalence with special symbols and the raw data set: C D Weedl 2.1 2.1 2.7 Weed 2.5 2.1 Note! Because of the limitations in software most special characters cannot be included in a 'pop-up answer format and yet they are needed for the hypothesis formation. The pop- up selections will be in the text-form for the special characters embedded within the pop-up answer. Use the table at the right as a guide if needed Special English Text Character Equivalence H2 mu 1, mu-2 11.12 eta-1, eta-2 03.03 sigma 1, sigma2 Р. Р. D-1, 2 xbar 1, x-bar 2 XXXtilde-1, x-tilde 2 Pulla p hat 1. p hat-2 not equal 2 or cor А B 1 Humboldt Oregon 2 16 16.4 3 7.4 17.6 4 15.8 89 5 145 20.4 6 7.8 9.8 7 14.2 17.5 9 74 10 51 12 13 10 1.8 2.9 2.4 2.3 2.2 . 2.2 2.3 1.9 2 2.2 24 2.5 2.4 23 24.3) Step 2 Declare the variables for this hypothesis test: mu-1 The mean density of whelk population on the Humboldt county coast per 0.25 m mu-2 ✓ The mean density of whelk population on the central Oregon coast per 0.25 m2

24.3) Step 3) Choose the correct hypothesis statement to test the graduate student's claim that the Humboldt county coat has a smaller whelk density than the central Oregon coast. Test the hypothesis at a 10% LOS H: mu-1 mu-2 H: mu-1 < mu-2 Q = 0.10 24.3), Step 4) Write a statistical conclusion for the hypothesis using output from R for a two-sample t-test with pooled variances, At the 10% LOS We Do Not Reject the null hypothesis of H, because: t-Notation and df Support: trample and df 12 P-Notational Support: P> Numeria Validation P = v 0.10

24.3), Step 5) Write an English sentence conclusion The evidence supports the case that Humboldt county coast does not have a lower whelk density than that of the central Oregon coast.